Determinants of outcome in melanoma patients with cerebral metastases

PURPOSE

To analyze prognostic factors, effects of treatment, and survival for patients with cerebral metastases from melanoma.

PATIENTS AND METHODS

All melanoma patients with cerebral metastases treated at the Sydney Melanoma Unit between 1952 and 2000 were identified. From 1985 to 2000, patients were diagnosed and treated using consistent modern techniques and this cohort was analyzed in detail. Multivariate analysis of prognostic factors for survival was performed.

RESULTS

A total of 1137 patients with cerebral metastases were identified; 686 were treated between 1985 and 2000. For these 686 patients, the median time from primary diagnosis to cerebral metastasis was 3.1 years (range, 0 to 41 years). A total of 646 patients (94%) have died as a result of melanoma. The median survival from the time of diagnosis of cerebral metastasis was 4.1 months (range, 0 to 17.2 years). Treatment was as follows: surgery and postoperative radiotherapy, 158 patients; surgery alone, 47 patients; radiotherapy alone, 236 patients; and supportive care alone, 210 patients. Median survival according to treatment received for these four groups was 8.9, 8.7, 3.4, and 2.1 months, respectively; the differences between surgery and nonsurgery groups were statistically significant. On multivariate analysis, significant factors associated with improved survival were surgical treatment (P <.0001), no concurrent extracerebral metastases (P <.0001), younger age (P =.0007), and longer disease-free interval (P =.036). Prognostic factors analysis confirmed the important influence of patient selection on treatment received.

CONCLUSION

This large series documents the characteristics of patients who developed cerebral metastases from melanoma. Median survival was dependent on treatment, which in turn was dependent on patient selection.

Pseudotumor cerebri syndrome: venous sinus obstruction and its treatment with stent placement

OBJECT

Pseudotumor cerebri, or benign intracranial hypertension, is a condition of raised intracranial pressure in the absence of a mass lesion or cerebral edema. It is characterized by headache and visual deterioration that may culminate in blindness. Pseudotumor cerebri is caused by venous sinus obstruction in an unknown percentage of cases. The purpose of this study was to investigate the role of cerebral venous sinus disease in pseudotumor cerebri and the potential of endoluminal venous sinus stent placement as a new treatment.

METHODS

Nine consecutive patients in whom diagnoses of pseudotumor cerebri had been made underwent examination with direct retrograde cerebral venography (DRCV) and manometry to characterize the morphological features and venous pressures in their cerebral venous sinuses. The cerebrospinal fluid (CSF) pressure was measured simultaneously in two patients. If patients had an amenable lesion they were treated using an endoluminal venous sinus stent. Five patients demonstrated morphological obstruction of the venous transverse sinuses (TSs). All lesions were associated with a distinct pressure gradient and raised proximal venous sinus pressures. Four patients underwent stent insertion in the venous sinuses and reported that their headaches improved immediately after the procedure and remained so at 6 months. Vision was improved in three patients, whereas it remained poor in one despite normalized CSF pressures.

CONCLUSIONS

Patients with pseudotumor cerebri should be evaluated with DRCV and manometry because venous TS obstruction is probably more common than is currently appreciated. In patients with a lesion of the venous sinuses, treatment with an endoluminal venous sinus stent is a viable alternative for amenable lesions.

Pseudotumour cerebri, CSF rhinorrhoea and the role of venous sinus stenting in treatment

We present a case of pseudotumour cerebri (PTC), which is important as it illustrates the effects of chronically raised CSF pressure, the relationship between PTC and venous sinus obstruction and the successful treatment of PTC using a venous sinus stent. A 38-year-old woman, previously diagnosed with PTC and unsuccessfully treated 10 years previously re-presented with spontaneous CSF rhinorrhoea. Imaging revealed dramatic changes of chronically raised CSF pressure and a defect in the anterior cranial fossa. The CSF leak was corrected surgically and a lumbo-peritoneal shunt inserted to correct a large postoperative subgaleal CSF collection. Direct retrograde cerebral venography (DRCV) demonstrated venous sinus obstruction due to a filling defect. This was associated with a pressure gradient and a high superior sagittal sinus pressure. The venous sinus obstruction was successfully treated with a venous sinus stent and the lumbo-peritoneal shunt was removed. Chronically raised CSF pressure in untreated cases of PTC may cause widespread changes in the skull, which in this case, culminated in a spontaneous CSF leak despite relatively mild headache and visual symptoms. Furthermore, cases of PTC secondary to venous sinus obstruction may be successfully treated using venous sinus stenting. The index of suspicion for venous sinus stenosis or obstruction should be raised in the investigation of patients with PTC.

Neuroimaging findings in a suprasellar granular cell tumor

A 27-year-old woman presented with a history of amenorrhea, visual disturbance, and diabetes insipidus. Magnetic resonance imaging showed a large enhancing suprasellar mass with associated edema involving the left striatum. The lesion was hypometabolic on fluorodeoxyglucose-positron emission tomography. At surgery, a subtotal resection of a vascular tumor that appeared to arise from the posterior pituitary and hypothalamus was carried out. Pathologic examination revealed a granular cell tumor. We report the preoperative neuroimaging findings in this rare posterior pituitary stalk tumor.

Surgical management of cerebral metastases from melanoma: outcome in 147 patients treated at a single institution over two decades

OBJECT

The aim of this study was to review the outcome of patients who underwent surgery for treatment of cerebral metastatic melanoma.

METHODS

A retrospective analysis was performed in 147 patients with cerebral metastases from melanoma who were treated surgically at a single institution between 1979 and 1999. Almost all patients underwent postoperative wholebrain radiation therapy. The mean patient age was 53 years (range 17-76 years); 69% of patients were male. A single cerebral metastasis was identified in 84% of patients, although 56% had synchronous extracranial metastases. The 30-day postoperative mortality rate was 2% and neurological symptoms resolved or improved in 78% of patients. Recurrence of intracerebral disease was seen in 55% of patients and 26% died of intracerebral metastases. Twenty-four patients underwent reoperation for recurrent cerebral disease. The median survival duration from the time of surgery for all patients was 8.5 months; the 3- and 5-year survival rates were 9% and 5%, respectively. Factors that significantly influenced survival on univariate analysis were the number of cerebral metastases (p = 0.015), a macroscopically complete excision (p < 0.05), and reoperation for recurrence (p = 0.02). The presence of extracranial metastases did not significantly influence survival. On multivariate analysis only the number of cerebral metastases significantly affected survival (p = 0.04).

CONCLUSIONS

For the majority of patients with cerebral metastases from melanoma, surgery with adjuvant radiation therapy is a treatment option that improves neurological symptoms and produces minimal morbidity. Long-term survival (> 3 years) most likely occurs in patients with a single cerebral metastasis and no demonstrable extracranial disease. Reoperation for recurrent cerebral disease may be appropriate in selected cases.

Dopamine interacts directly with its D3 and D2 receptors on normal human T cells, and activates beta1 integrin function

Dopamine by itself has not up to now been reported to activate T cell function. We show here that dopamine interacts directly with dopaminergic receptors on normal human T cells and triggers beta1 integrin-mediated T cell adhesion to a major extracellular matrix component, fibronectin (FN). Such adhesion is a characteristic feature of activated T cells, and is critical for trafficking and extravasation of T cells across blood vessels and tissue barriers. Seven dopamine D2/D3 receptor agonists and antagonists were used to identify the receptor subtypes with which dopamine specifically interacts to activate T cells. The D3 dopamine receptor agonist, 7-hydroxy-DPAT (DPAT), mimics the effects of dopamine, and the effects of both dopamine and DPAT are blocked by a specific D3 receptor antagonist, U-maleate. The dopamine receptor agonists bromocriptine and pergolide mimic the direct effect of dopamine on the beta1 integrin function, while the dopamine receptor antagonists butaclamol and haloperidol suppress it, suggesting additional signaling via the dopamine D2 receptor subtype. Our study shows, for the first time, that dopamine can directly activate T cells via ist specific receptors and suggests a possible role for dopamine in integrin-mediated cellular trafficking and extravasation of T cells in the central nervous system and possibly also in the periphery. Finally, we suggest that the reported changes in the D3 and D2 receptor RNA levels in peripheral blood lymphocytes of individuals with schizophrenia, Parkinson's disease, Alzheimer's disease and migraine can serve not only as a 'passive' diagnostic marker, but primarily reflect the dynamic functional dopamine-T cell interactions in these diseases.

The FX enzyme is a functional component of lymphocyte activation

Fucose is an essential constituent of selectin ligands. These molecules mediate the initial contact between extravasating leukocytes and endothelial cells. The generation of GDP-L-fucose by the FX enzyme is the final step of fucose biosynthesis. Recently, we demonstrated that outside-in signaling regulates the expression of the FX enzyme in certain cancer cells. The present study demonstrates that the polyclonal activation of T and B cells significantly up-regulated the expression of the FX enzyme and of the fucosylated selectin ligands sLe-x and CLA. Treatment of T cells with FX antisense oligonucleotides significantly decreased selectin ligand expression upon activation. We conclude that FX is regulated by outside-in signals also in lymphocytes and that this enzyme is involved in the biosynthesis of selectin ligands in such cells. We propose that FX takes part in the cascade of events leading to the extravasation of activated lymphocytes.

Idiopathic gonadotrophin deficiency: genetic questions addressed through phenotypic characterization

OBJECTIVE

The association of idiopathic hypogonadotrophic hypogonadism (IHH) with congenital olfactory deficit defines Kallmann's syndrome (KS). Although a small proportion of IHH patients have been found to harbour defined genetic lesions, the genetic basis of most IHH cases remains to be elucidated. Genes currently recognized to be involved comprise KAL (associated with X-linked-KS), the GnRH receptor (associated with resistance to GnRH therapy), DAX 1 (associated with adrenohypoplasia congenita) and three loci also associated with obesity, leptin (OB), leptin receptor (DB) and prohormone convertase (PC1). Because of the rarity of the condition and the observation that patients are almost universally infertile without assistance, familial transmission of IHH is encountered infrequently and pedigrees tend to be small. This has constrained the ability of conventional linkage studies to identify other candidate loci for genetic IHH. We hypothesized that a systematic clinical evaluation of a large patient sample might provide new insights into the genetics of this rare disorder. Specifically, we wished to examine the following propositions. First, whether normosmic (nIHH) and anosmic (KS) forms of IHH were likely to be genetically discrete entities, on the basis of quantitative olfactory testing, analysis of autosomal pedigrees and the prevalence of developmental defects such as cryptorchidism and cleft palate. Second, whether mirror movements and/or unilateral renal agenesis were specific phenotypic markers for X-linked-KS.

DESIGN AND PATIENTS

We conducted a clinical study of 170 male and 45 female IHH patients attending the endocrinology departments of three London University teaching hospitals. Approximately 80% of data were obtained from case records and 20% collected prospectively. Parameters assessed included olfaction, testicular volume, family history of hypogonadism, anosmia or pubertal delay, and history or presence of testicular maldescent, neurological, renal or craniofacial anomalies. Where possible, the clinical information was correlated with published data on genetic analysis of the KAL locus.

RESULTS

Olfactory acuity was bimodally distributed with no evidence for a spectrum of olfactory deficit. Testicular volume, a marker of integrated gonadotrophin secretion, did not differ significantly between anosmic and normosmic patients, at 2.0 ml and 2.2 ml, respectively. Nevertheless, the prevalence of cryptorchidism was nearly three times greater in anosmic (70.3%, of which 75.0% bilateral) than in normosmic (23.2%, of which 43.8% bilateral) patients. Individuals with nIHH, eugonadal isolated anosmia and/or KS were observed to coexist within 6/13 autosomal IHH pedigrees. On three occasions, fertility treatment given to an IHH patient had resulted in the condition being transmitted to the resulting offspring. Mirror movements and unilateral renal agenesis were observed in 24/98 and 9/87 IHH patients, respectively, all of whom were identifiable as X-KS males on the basis of pedigree analysis and/or defective KAL coding sequence. Abnormalities of eye movement and unilateral sensorineural deafness were observed in 10/21 and 6/111 KS patients, respectively, but not in nIHH patients.

DISCUSSION

Patients with IHH are almost invariably either anosmic (KS) or normosmic (nIHH), rather than exhibiting intermediate degrees of olfactory deficit. Moreover, the prevalence of cryptorchidism is nearly three times greater in KS than in nIHH despite comparable testicular volumes, suggesting a primary defect of testicular descent in KS independent of gonadotrophin deficiency. Disorders of eye movement and hearing appear only to occur in association with KS. Taken together, these findings indicate a clear phenotypic separation between KS and nIHH. However, pedigree studies suggest that autosomal KS is an heterogeneous condition, with incomplete phenotypic penetrance within pedigrees, and that some cases of autosomal KS, nIHH and even isolated anosmia are likely to have a common genetic basis. The prevalences of anosmia, mirror movements and unilateral renal agenesis among X-KS men are estimated to be 100, 85 and 31%, respectively. In sporadic IHH, mirror movements and unilateral renal agenesis are 100% specific phenotypic markers of de novo X-KS. By comparison, only 7/10 X-KS families harboured KAL coding defects. Clinical ascertainment, using mirror movements, renal agenesis and ichthyosis as X-KS-specific phenotypic markers, suggested that de novo X-KS was unlikely to comprise more than 11% of sporadic cases. The majority of sporadic KS cases are therefore presumed to have an autosomal basis and, hence, the preponderance of affected KS males over females remains unexplained, though reduced penetrance in women would be a possibility.

Colloid cyst of the third ventricle: a clinical review of 39 cases

This paper is a retrospective review of all patients treated for a colloid cyst of the third ventricle at Royal Prince Alfred Hospital over an 18-year consecutive period. Our experience is fairly typical compared with other published series. Colloid cys ts made up 1.6% of tumours treated by the neurosurgical unit. Patients presented with non-specific neurological symptoms and signs, commonly suggestive of raised intracranial pressure. Microsurgical excision was carried out via the transcallosal route in 34 cases and the transfrontal approach in four cases. There was no apparent difference in results from the different surgical approaches. In 86% of patients reviewed after more than 6 months good long term outcome was achieved. These benign tumours can be safely cured if the diagnosis is made early and the cyst removed by careful microsurgical techniques.

Intracavernous schwannoma of the abducens nerve: a review of the clinical features, radiology and pathology of an unusual case

We report a case of an intracavernous abducens nerve schwannoma presenting in a 19 year old male of Mediterranean origin. This is only the second report of an abducens nerve schwannoma located entirely within the cavernous sinus. The lesion resulted in a progressive diplopia and focal abducens palsy. The clinical, radiological and pathological features are presented. A literature search has identified only four other abducens nerve schwannomas arising completely or partly within the cavernous sinus. We review these cases and aspects of other ocular cranial nerve schwannomas.

Transcranial Doppler in carotid endarterectomy

PURPOSE

To evaluate the role of transcranial Doppler monitoring in reducing the complications of carotid endarterectomy, by analysing: (1) perioperative intracerebral blood flow velocity; (2) embolic load; and (3) effect of Dextran-40 therapy on patient outcome.

DESIGN

Retrospective case series.

METHODS

The study cohort consisted of 30 consecutive patients undergoing 32 carotid endarterectomy procedures. Continuous transcranial Doppler (TCD) monitoring of the ipsilateral middle cerebral artery (MCA) was performed to obtain flow velocities and embolic count. Flow velocity changes were analysed in relation to electroencephalographic (EEG) changes. A Dextran-40 infusion was instituted for patients who experienced a post-arteriotomy embolic load of >50 counts/hour.

RESULTS

The average middle cerebral artery velocity (MCAvel) drop on cross clamping was 46+/-12.1%, expressed as a percentage of the individual's 24-hour pre-operative value. Clamping ischaemia developed in six cases (18.8%) of which three (9.4%) demonstrated TCD changes only, and three demonstrated both TCD and EEG changes (9.4%). The average increase in MCAvel at 60-120 minutes postarteriotomy, was 18+/-17.5%; six cases developed hyperaemia. Postoperative emboli were seen in 88% of cases with 31% of patients demonstrating embolic loads of >50/hour.

CONCLUSIONS

Perioperative transcranial Doppler monitoring (1) is a useful adjunct to EEG assessment of cross clamping ischaemia, providing information in real time, on MCA blood velocity deterioration that may antecede irreversible change (2) detects postoperative hyperaemic response, and (3) allows quantification of microembolic loads that, when high, have been shown to be a precursor to localised cerebral ischaemia and can be effectively treated with Dextran-40 infusion.

Cutting edge: clonally restricted production of the neurotrophins brain-derived neurotrophic factor and neurotrophin-3 mRNA by human immune cells and Th1/Th2-polarized expression of their receptors

Neurotrophins, such as neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF), are potent regulators of neuronal functions. Here we show that human immune cells also produce NT-3 mRNA, secrete BDNF, and express their specific receptors trkB and trkC. The truncated trkB receptor, usually expressed in sensory neurons of the central nervous system, was also constitutively expressed in unstimulated Th cells. Full-length trkB was detectable in stimulated PBMC, B cell lines, and Th1, but not in Th2 and Th0 cell clones. Clonally restricted expression was also observed for trkC, until now not detected on blood cells. The Th1 cytokine IL-2 stimulated production of trkB mRNA but not of trkC, whereas the Th2 cytokine IL-4 enhanced NT-3 but not BDNF mRNA expression. Microbial Ags, which influence the Th1/Th2 balance, could therefore modulate the neurotrophic system and thereby affect neuronal synaptic activity of the central nervous system.

The acquired Chiari malformation and syringomyelia following spinal CSF drainage: a study of incidence and management

Firstly, 14 patients are described who developed either an acquired Chiari malformation (ACM) alone (7 cases) or ACM and syringomyelia (7 cases) after lumbar subarachnoid space (SAS) shunting or in one case, epidural anaesthesia with SAS penetration. Four groups are considered: 3 cases with craniofacial dysostosis and communicating hydrocephalus (CH), 4 cases with CH alone, 3 cases with pseudotumour cerebri (PTC) and a miscellaneous group (4 cases). Initial treatment was varied: resiting the shunt to ventricle or cisterna magna [6], adding an H-V valve [1], syrinx shunting [4] and posterior fossa decompression [3]. Further treatment was required in 6 cases. Secondly, incidence was examined in 87 patients with PTC initially treated either by lumbar SAS shunting [70] or cisterna magna shunting [17]. In the first sub-group, 11 cases (15.7 per cent) developed an ACM, 3 symptomatic (as above) and eight asymptomatic with 1 case also having syringomyelia whereas 1 case occurred in the second group with a questionanably symptomatic ACM. While accurate for symptomatic lesions, these figures are tentative with respect to asymptomatic lesions due to inadequate pre-treatment radiology and detailed MR follow-up. The main conclusions are, first, that the incidence of symptomatic ACM and/or syringomyelia is not high enough to warrant abandoning SAS shunting; second that asymptomatic lesions need not necessarily be treated and third, that when treatment is required, shunt resiting is the first choice.

Acromegaly, colonic polyps and carcinoma

OBJECTIVE

It has been suggested that patients with acromegaly may be at risk of developing colorectal carcinoma. In order to clarify this issue, we have evaluated the prevalence of carcinoma, premalignant tubulovillous adenomas and hyperplastic colonic polyps in a large cohort of patients with acromegaly.

DESIGN

Prospective colonoscopic examination by a single operator.

PATIENTS

One hundred and twenty-nine patients with biochemically proven acromegaly.

RESULTS

At least one lesion was visualized in 63 patients. Adenocarcinoma was present in six patients (5%), but only two had symptoms; all lesions were endoscopically obvious. Compared with a normal group, the odds ratio of colorectal cancer is increased at 13.5 (95% confidence intervals (c.i.) 3.1-75). One or more tubulovillous adenoma was found in 34 patients (26%) and this prevalence was age-dependent, occurring in 39% of patients aged 70 years or over. Comparing the prevalence of left-sided colonic adenomas with that in a normal group, there is a higher prevalence among patients over 49 years with an odds ratio of 4.2 (95% c.i. 2.5-6.8). Patients with acromegaly who had an adenoma were significantly older than unaffected patients (61.9 vs 54.1 years; P < 0.001) but had similar GH and IGF-1 levels and duration of disease.

CONCLUSIONS

Patients with acromegaly have an increased risk of developing colorectal cancer and a significantly higher prevalence of tubulovillous adenomas compared with normal subjects. Routine surveillance colonoscopy is indicated in this group of patients.

Competency-based learning in traumatology

BACKGROUND

A multidisciplinary, competency-based trauma teaching program was introduced for final year medical students (n = 67) at Royal Prince Alfred Hospital (RPAH) in 1994 to complement the surgical clerkship.

METHODS

The method involved small groups rotating through a series of teaching stations each structured to address a predetermined competency. Four 3-hour sessions were held on the subject areas of resuscitation, plastic, orthopedic, and neurotrauma. Performance in the trauma section of a summative Objective Structured Clinical Examination (OSCE), 6 months after the teaching, was compared with that of a control group (n = 127) from other campuses where trauma was taught by a series of discipline-based lectures. Three trauma OSCE stations were designed to test psychomotor skills while five addressed aspects of the cognitive domain. Checklists were used to ensure standardization of scoring in a range of questions asked for skills tested at each station.

RESULTS

The marks of the RPAH students (mean 78% +/- SD 9%) were significantly higher (P < 0.0005) than the controls (mean 70% +/- SD 9%) in the 8 trauma questions. There was no significant difference (P = 0.8) in marks obtained by the study group (mean 61% +/- SD 8%) and controls (mean 63% +/- SD 7%) in 22 questions sampling a wide spectrum of nontrauma subject areas. The study group performed significantly better in one of the three skills stations and three of the five problem-solving stations when compared with the control group.

CONCLUSION

The innovation has the potential to fulfill a need for an integrated trauma program in the undergraduate core curriculum.

Pheochromocytoma: effect of nonionic contrast medium in CT on circulating catecholamine levels

PURPOSE

To study the catecholamine-releasing effect of peripheral intravenous administration of the nonionic contrast medium iohexol in patients with pheochromocytomas.

MATERIALS AND METHODS

Ten patients (eight women, two men; mean age, 44 years; age range, 25-70 years) with pheochromocytomas and related tumors and six healthy volunteers (five men, one woman; mean age, 31 years; age range, 27-35 years) were examined. Plasma catecholamine levels were measured at intervals for 60 minutes after the injection of 0.9% saline or iohexol on 2 separate days. All 10 patients intravenously received the specific alpha-adrenergic blocker phenoxybenzamine hydrochloride (0.5 mg/kg in 250 mL of 5% dextrose infused over 2 hours) 24 hours before iohexol-enhanced computed tomography.

RESULTS

There was no statistically significant increase in epinephrine or norepinephrine levels in the patients or the control subjects.

CONCLUSION

While it may be prudent to administer oral alpha- and beta-adrenoceptor antagonists in all patients with a biochemically proved pheochromocytoma to control their symptoms and to prevent a spontaneous adrenergic crisis, specific blockade may not be required before contrast medium-enhanced scanning with iohexol. Although the sample size of this study is relatively small, the results do suggest that in an incidentally detected, clinically silent adrenal mass that may or may not be hypersecreting, the nonionic contrast medium iohexol may be used for scanning without blockade.

A combined test using desmopressin and corticotropin-releasing hormone in the differential diagnosis of Cushing's syndrome

To assess the ability of desmopressin to differentiate between pituitary and ectopic ACTH-dependent Cushing's syndrome and to determine whether diagnostic accuracy could be improved by administering it together with human sequence CRH, we examined its effects on cortisol and ACTH secretion when given alone or in combination with CRH in patients with Cushing's syndrome of varied etiology and compared these data to the results of a standard CRH test in the same individuals. Each patient was studied on three occasions, in random order, separated by at least 48 h. At 0900 h, via an indwelling forearm cannula, 10 micrograms desmopressin, 100 micrograms CRH, or a combination of the two were given as an iv bolus; thereafter, blood was drawn every 15 min for 2 h. The responses to the individual agents were determined according to the timing and calculation criteria suggested by Nieman et al. (1993). A total of 25 patients with Cushing's syndrome were studied: 17 patients with pituitary-dependent Cushing's syndrome, Cushing's disease (CD); 5 patients with occult ectopic ACTH secretion (EC); and 3 patients with primary adrenal (ACTH-independent) Cushing's syndrome. In this series, the best discrimination among ACTH-dependent patient groups was achieved using the combined test. Using the responses of plasma cortisol, all 17 patients with CD showed a rise greater than any of the 5 patients with EC, whereas 1 patient with CD showed a plasma ACTH response within the range seen in the patients with EC. Plasma cortisol responses to desmopressin alone were seen in 14 of 17 patients with CD and 1 of 5 patients with EC and, after CRH alone, in 15 of 17 patients with CD but in no patient with EC. In contrast, plasma ACTH responses after CRH alone were seen in 14 of 17 patients with CD and 2 of 5 patients with EC and, after desmopressin alone, in 12 of 17 with CD and 3 of 5 with EC, thus indicating overlapping responses between the groups and poorer discrimination. No responses were seen in the ACTH-independent group. These data indicate that desmopressin causes the secretion of ACTH and cortisol in patients with ACTH-dependent Cushing's syndrome, and that in combination with CRH, it may provide an improvement over the standard CRH test in the differential diagnosis of ACTH-dependent Cushing's syndrome. Furthermore, these data suggest that there may be abnormalities in vasopressin receptor function or number in ACTH-secreting tumors.